54 TUBERCULIN DIAGNOSIS 



of tuberculosis, as there are many normal individuals who react to a 4 per 

 cent, tuberculin concentration. 



Instead of the tuberculin solution, Wolff-Eisner recommends a 2 per 

 cent, old tuberculin lanolin ointment. The lower lid of the eye is pulled 

 downward and a pea- sized mass of the ointment is gently placed into the 

 conjunctival sac by means cf a sterile glass rod. The lid is held fixed for 

 about a minute. 



The ophthalmo reaction is indicated in all suspicious cases of 

 Indications tuberculosis where the presence of bacilli cannot be demon- 



, , , -r, strated and where the subcutaneous reaction either on account 

 tnalmo Re- 

 actions. f the presence of temperature or other reasons cannot be 



undertaken. 



This test is much milder and more agreeable to the patient than the sub- 

 cutaneous one, and in ambulatory work more significant, inasmuch as it 

 does away with any necessity for considering as a guide the temperature 

 taken by the untrained and usually unreliable patient. 



The ophthalmo reaction is contraindicated in all diseases of 

 Contraindi- ^ e e y e ^ tuberculous or otherwise. If one eye only is affected, 



ca 1 tl J? s r the reaction should not be undertaken upon the healthy eye. 



the Oph- r ,. J , 



thalmo Re- Similarly, patients who have had some eye disease, even though 



action, many years ago, those who by reason of their occupation are 



readily exposed to eye diseases, or who live in districts where 



trachoma is prevalent, should be excluded from the test. The reason being 



that in those individuals the conjunctival mucous membrane becomes a 



locus minoris resistentiae and therefore easily inflamed. 



Repeated instillations of tuberculin into the same eye may set up very 

 severe disturbances. Scrofulous children often show reactions of the third 

 degree, inasmuch as they possess the constitutional tendency which makes 

 them easily susceptible to conjunctivitis or phlyctenulse. In patients with 

 a positive ophthalmo reaction that has subsided, a recurrence of the con- 

 junctival inflammation is frequently observed when they begin to receive 

 subcutaneous inoculations of tuberculin for therapeutic or diagnostic 

 purposes. 



The Specificity of the Tuberculin Reaction. 



I'he one real essential for the practical application of all biological reactions is 

 the specificity of the reaction. There is, however, as will be repeatedly pointed out 

 further on, no single absolutely specific reaction. In fact, it would be more exact to 

 consider these biological reactions only relatively specific; the latter depending upon 

 the quantity of the required antigen and the reacting organism. In this connection it 

 may also be said, that it is never possible to draw an exact line between the specific 

 and non-specific biological reactions. There always will be a doubtful zone. As a 

 general rule, however, the smaller the quantity of antigen that is required and the 

 stronger the resulting reaction, the more probable is the biological specificity. 



